Think: A Compelling Introduction to Philosophy (4 page)

There are six Meditations. In the first, Descartes introduces the
`method of doubt'. He resolves that if he is to establish anything in
the sciences that is`stable and likely to last' he must demolish all his
ordinary opinions, and start right from the foundations.

For he has found that even his senses deceive him, and it is 'prudent never to trust completely those who have deceived us even
once'. He puts to himself the objection that only madmen ('who
say that they are dressed in purple when they are naked, or that
their heads are made of earthenware, or that they are pumpkins or
made of glass'-madmen were evidently pretty colourful in the
seventeenth century) deny the very obvious evidence of their
senses.

In answer to that, he reminds us of dreams, in which we can represent things to ourselves just as convincingly as our senses now
do, but which bear no relation to reality

Still, he objects to himself, dreams are like paintings. A painter
can rearrange scenes, but ultimately depicts things derived from
`real' things, if only real colours. By similar reasoning, says
Descartes, even if familiar things (our eyes, head, hands, and so oil) are imaginary, they must depend on some simpler and more universal things that are real.

But what things? Descartes thinks that `there is not one of my
former beliefs about which a doubt may not properly be raised'.
And at this stage,

I will suppose therefore that not God, who is supremely good
and the source of truth, but rather some malicious demon of
the utmost power and cunning has employed all his energies
in order to deceive me. I shall think that the sky, the air, the
earth, colours, shapes, sounds and all external things are
merely the delusions of dreams which he has devised to ensnare my judgment.

This is the Evil Demon. Once this frightening possibility is raised,
his only defence is resolutely to guard himself against believing any
falsehoods. He recognizes that this is hard to do, and `a kind of laziness' brings him back to normal life, but intellectually, his only
course is to labour in the `inextricable darkness' of the problems he
has raised. This ends the first Meditation.

COGITO, ERGO SUM

The second Meditation begins with Descartes overwhelmed by
these doubts. For the sake of the inquiry he is supposing that `I have
no senses and no body'. But:

Does it now follow that I too do not exist? No: if I convinced
myself of something then I certainly existed. But there is a
deceiver of supreme power and cunning who is deliberately and constantly deceiving me. In that case I too undoubtedly
exist, if he is deceiving me; and let him deceive me as hutch as
he can, he will never bring it about that I am nothing so long
as I think that I ant something. So after considering everything very thoroughly, I must finally conclude that this proposition, I am, I exist, is necessarily true whenever it is put
forward by me or conceived in my mind.

This is the famous `Cogito, ergo sum': `I think, therefore I am.'

Having saved his `self' out of the general seas of scepticism,
Descartes now asks what this self is. Whereas formerly, he thought
he knew what his body was, and thought of himself by way of his
body, now he is forced to recognize that his knowledge of his self is
not based on knowledge of his embodied existence. In particular,
he is going to meet problems when he tries to imagine it. Imagination is a matter of contemplating the shape or image of a corporeal
thing (a body, or thing extended in space). But at this stage, we
know nothing of corporeal things. So `imagining' the self by
imagining a thin or tubby, tall or short, weighty bodily being, such
as I see in a mirror, is inadequate.

So what is the basis of this knowledge of the self?

Thinking?At last I have discovered it-thought; this alone is
inseparable from me. I am, I exist-that is certain. But for
how long? For as long as I am thinking. For it could be, that
were I totally to cease from thinking, I should totally cease to
exist.... I am, then, in thestrict sense only a thing that thinks.

The inquiry now takes a slightly different course. Descartes recognizes that a conception of oneself as an embodied thing, living in
an extended spatial world of physical objects, will come back al most irresistibly. And he realizes that the `I' he is left with is pretty
thin: `this puzzling I that cannot be pictured in the imagination. So
'let us consider the things which people commonly think they understand most distinctly of all; that is the bodies we touch and see.
He considers a ball of wax. It has taste and scent, and a colour,
shape, and size `that are plain to see'. If you rap it, it makes a sound.
But now he puts the wax by the fire, and look:

/The residual taste is eliminated, the smell goes away, the
colour changes, the shape is lost, the size increases; it becomes
liquid and hot; you can hardly touch it, and if you strike it, it
no longer makes a sound. But does the same wax remain? It
must be admitted that it does; no one denies it, no one thinks
otherwise. So what was it in the wax that I understood with
such distinctness? Evidently none of the features which I arrived at by means of the senses; for whatever came under
taste, smell, sight, touch or hearing has now altered-yet the
wax remains.

Descartes glosses the result of this example as showing that there is
a perception of the wax that is `pure mental scrutiny, which can become `clear and distinct' depending on how careful he is to concentrate on what the wax consists in. So, by the end of the second
Meditation, he concludes:

I now know that even bodies are not strictly perceived by the
senses or the faculty of imagination but by the intellect alone,
and that this perception derives not from their being touched
or seen but from their being understood; and in view of this I
know plainly that I can achieve an easier and more evident
perception of my own mind than of anything else.

MOTIVATIONS, QUESTIONS

Flow are we to read a piece of philosophy like this? We start by seeing Descartes trying to motivate his method of extreme doubt
(also known as Cartesian doubt, or as he himself calls it, `hyperbolic, that is, excessive or exaggerated doubt). But is the motivation satisfactory? What exactly is he thinking? Perhaps this:

The senses sometimes deceive us. So for all we know, they
always deceive us.

But that is a had argument-a fallacy. Compare:

Newspapers sometimes make mistakes. So for all we know,
they always make mistakes

The starting point or premise is true, but the conclusion seems
very unlikely indeed. And there are even examples of the argument
form where the premise is true, but the conclusion cannot be true:

Some banknotes are forgeries. So for all we know, they all
are forgeries.

Here, the conclusion is impossible, since the very notion of a
forgery presupposes valid notes or coins. Forgeries are parasitic
upon the real. Forgers need genuine notes and coins to copy.

An argument is valid when there is no way-meaning no possible way-that the premises, or starting points, could be true
without the conclusion being true (we explore this further in
Chapter 6). It is sound if it is valid and it has true premises, in which
case its conclusion is true as well. The argument just identified is
clearly invalid, since it is no better than other examples that lead us from truth to falsity. But this in turn suggests that it is uncharitable
to interpret Descartes as giving us such a sad offering. We might interpret him as having in mind something else, that he regrettably
does not make explicit. This is called looking for a suppressed
premise-something needed to buttress an argument, and that its
author might have presupposed, but does not state. Alternatively
we might reinterpret Descartes to be aiming at a weaker conclusion. Or perhaps we can do both. The argument might be:

The senses sometimes deceive us. We cannot distinguish
occasions when they do from ones when they do not. So for
all we know, any particular sense experience may be deceiving us.

This seems to be a better candidate for validity. If we try it with
banknotes and forgeries, we will find that the conclusion seems to
follow. But the conclusion is a conclusion about any particular experience. It is no longer the conclusion that all our experience (en
bloc, as it were) may be deceiving us. It is the difference between
`for all we know any particular note may be a forgery' and `for all we
know all notes are forgeries'. The first may be true when the second
is not true.

Still, perhaps at this stage of the Meditations the weaker conclusion is all Descartes wants. But we might also turn attention to the
second premise of this refined argument. Is this premise true? Is it
true that we cannot distinguish occasions of error-things like illusions, delusions, misinterpretations of what we are seeingfrom others? To think about this we would want to introduce a
distinction. It may be true that we cannot detect occasions of illusion and error at a glance. That is what makes them illusions.
But is it true that we cannot do so given time? On the contrary, it
seems to be true that we can do so: we can learn, for instance, to
mistrust images of shimmering water in the desert as typically misleading illusions or mirages-tricks of the light. But worse, the fact
that we can detect occasions of deception is surely presupposed by
Descartes's own argument. Why so? Because Descartes is presenting the first premise as a place to start from-a known truth. But
we only know that the senses sometimes deceive us because further
investigations-using the very same senses-show that they have
done so. We find out, for instance, that a quick glimpse of shimmering water misled us into thinking there was water there. But we
discover the mistake by going closer, looking harder, and if necessary touching and feeling, or listening. Similarly, we only know, for
instance, that a quick, off-the-cuff opinion about the size of the
Sun would be wrong because further laborious observations show
us that the Sun is in fact many times the size of the Earth. So the
second premise only seems true in the sense of'we cannot distinguish at a glance whether our senses are deceiving us. Whereas to
open the way to Descartes's major doubts, it would seem that he
needs `we cannot distinguish even over time and with care whether
our senses are deceiving us'. And this last does not seem to be true.
We might try saying that the senses are `self-corrective': further
sense experience itself tells us when a particular sense experience
has induced us to make a mistake.

Perhaps anticipating this kind of criticism Descartes introduces
the topic of dreams. `Inside' a dream we have experiences which
bear some resemblance to those of ordinary living, yet nothing real corresponds to the dream. Is Descartes's idea here that the whole of
experience may be a dream? If so, once again we might use a distinction like the one we just made: perhaps we cannot distinguish
immediately or `at a glance' whether we are dreaming, but using
our memory, we seem to have no trouble distinguishing past
dreams from past encounters with reality.

Still, there is something troubling about the idea that all experience might be a dream. For how could we set about determining
whether that is true? Sometimes people `pinch themselves' to ensure that they are not dreaming. But is this really a good test? Might
we not just dream that the pinch hurts? We might try from within
a dream to discover whether it is a dream. Yet even if we think up
some cunning experiment to determine whether it is, might we not
just dream that we conduct it, or dream that it tells us the answer
that we are awake?

We might try saying that events in everyday life exhibit a scale
and a sheer coherence that dreams do not exhibit. Dreams are jerky
and spasmodic. They have little or no rhyme or reason. Experience, on the other hand, is large and spacious and majestic. It goes
on in regular ways-or at least we think it does. However, it is then
open for Descartes to worry whether the scale and coherence is itself deceptive. That takes him to the Evil Demon, one of the most
famous thought-experiments in the history of philosophy. It is a
thought-experiment designed to alert us to the idea that, so far as
truth goes, all our experience might be just like a dream: totally disconnected from the world.